Martin Luther, commenting on Galatians 5:5, wrote:
Let us learn, therefore, that amid great and horrible terrors, when the conscience feels nothing but sin and supposes that God is wrathful and Christ is hostile, we must not consult the consciousness of our own heart. No, then we must consult the Word of God, which says that God is not wrathful, but that He has regard for those who are afflicted, are contrite in spirit, and tremble at His Word (Is. 66:2), and that Christ does not turn away from those who labor and are heavy-laden (Matt. 11:28) but revives them. Therefore this passage teaches clearly that the Law and works do not bring righteousness and comfort, but that this is achieved by the Spirit through faith in Christ; amid anxieties and tribulations He arouses hope, which endures and conquers evil. Very few people know how weak and feeble faith and hope are in cross and conflict; then faith and hope seem to be “a dimly burning wick” (Is. 42:3), which a strong wind is about to blow out. But those who in hope believe against hope (Rom. 4:18) amid these conflicts and fears; that is, those who fight against the consciousness of sin, and of the wrath of God by faith in the promise of Christ, eventually experience that this poor little spark of faith (as it seems to reason, because it is hardly aware of it) will become like elemental fire, which fills all heaven and swallows up all terrors and sins.
Luther, Martin Luther’s Works, volume 27: Lectures on Galatians 27